#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
    FILE *fin, *fout;
    char tmp, str[305];
    fin = fopen("in.txt", "r");
    fout = fopen("out.txt", "w");
    if((fin=fopen("in.txt", "r")) == NULL)
    {
        printf("Fail to open!\n");
        exit(0);
    }
    while(~fscanf(fin, "%c", &tmp))
        fprintf(fout, "%c", tmp+3);
    fclose(fin);
    fclose(fout);
    fin = fopen("out.txt", "r");
    while(fgets(str, 305, fin) != NULL)
    {
        int i;
        for(i=0; i<strlen(str); i++)
            str[i] -= 3;
        printf("%s", str);
    }
    return 0;
}
